This is a competitive renewal application for a National Research Service Award (NRSA) Institutional Training grant (T32) for research training in pediatric urology at Boston Children's Hospital. For the past 10 years, this funding mechanism has supported the research component of our pediatric urology fellowship program. The pediatric urology fellowship at Boston Children's Hospital is the oldest and one of the most highly regarded such programs in the world. The Urology Department at BCH is one of the world's leading centers for pediatric urology and genitourinary reconstruction and has one of the largest research programs dedicated to basic urology research in the country. The department is home to the BCH Urological Diseases Research Center, a George O'Brien Urology Research Center funded by a P50 grant from the NIDDK. The overall goals of the program are: (1) to enhance the trainees' understanding of basic mechanisms of cell physiology, the molecular basis of disease, and their translation to clinical urology; (2) to teach state- of-the-art, hypothesis-driven research methodology relevant to both basic science and clinical research; and (3) to provide sufficient time and guidance for a mature postdoctoral experience in basic, translational or clinical studies relevant to the trainees' future clinical careers and academic leadership roles. In the most recent funding cycle, postdoctoral MD trainees who have completed urology residency have conducted research in one of two settings during 2 uninterrupted years of the 3-year fellowship: (i) laboratory-based studies of urogenital tract development, physiology and pathophysiology or (ii) clinical outcomes and health services research in conjunction with faculty at the Harvard School of Public Health. Trainees will also undergo didactic training in critical thinking and grant writing, biostatistics and the responsible conduct of research. Four postdoctoral positions are requested per year for 2 years of research training. Twenty-seven mentors comprising basic science and clinical faculty, from 8 programs will support the training program. The fellowship represents a unique combination of outstanding clinical and basic research training within one of the world's leading centers for academic medicine and biomedical science. It is designed to enable our graduates to establish their own competitive programs of scholarship and research during their careers as academic pediatric urologists. These clinician-scientists can then contribute to understanding the genitourinary system in fundamental terms and to translating basic research findings into clinical applications. The T32 Pediatric Urology Research Training mechanism is the major source of support for the fellows during the 2-year research component of their fellowship.